// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef IPC_IPC_SYNC_MESSAGE_FILTER_H_
#define IPC_IPC_SYNC_MESSAGE_FILTER_H_

#include <set>

#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_vector.h"
#include "base/synchronization/lock.h"
#include "ipc/ipc_sender.h"
#include "ipc/ipc_sync_message.h"
#include "ipc/message_filter.h"

namespace base {
class SingleThreadTaskRunner;
class WaitableEvent;
}

namespace IPC {
class SyncChannel;

// This MessageFilter allows sending synchronous IPC messages from a thread
// other than the listener thread associated with the SyncChannel.  It does not
// support fancy features that SyncChannel does, such as handling recursion or
// receiving messages while waiting for a response.  Note that this object can
// be used to send simultaneous synchronous messages from different threads.
class IPC_EXPORT SyncMessageFilter : public MessageFilter, public Sender {
public:
    // MessageSender implementation.
    bool Send(Message* message) override;

    // MessageFilter implementation.
    void OnFilterAdded(Sender* sender) override;
    void OnChannelError() override;
    void OnChannelClosing() override;
    bool OnMessageReceived(const Message& message) override;

protected:
    SyncMessageFilter(base::WaitableEvent* shutdown_event,
        bool is_channel_send_thread_safe);

    ~SyncMessageFilter() override;

private:
    friend class SyncChannel;

    void set_is_channel_send_thread_safe(bool is_channel_send_thread_safe)
    {
        is_channel_send_thread_safe_ = is_channel_send_thread_safe;
    }

    void SendOnIOThread(Message* message);
    // Signal all the pending sends as done, used in an error condition.
    void SignalAllEvents();

    // The channel to which this filter was added.
    Sender* sender_;

    // Indicates if |sender_|'s Send method is thread-safe.
    bool is_channel_send_thread_safe_;

    // The process's main thread.
    scoped_refptr<base::SingleThreadTaskRunner> listener_task_runner_;

    // The message loop where the Channel lives.
    scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;

    typedef std::set<PendingSyncMsg*> PendingSyncMessages;
    PendingSyncMessages pending_sync_messages_;

    // Messages waiting to be delivered after IO initialization.
    ScopedVector<Message> pending_messages_;

    // Locks data members above.
    base::Lock lock_;

    base::WaitableEvent* shutdown_event_;

    DISALLOW_COPY_AND_ASSIGN(SyncMessageFilter);
};

} // namespace IPC

#endif // IPC_IPC_SYNC_MESSAGE_FILTER_H_
